1. Field of the Invention
The present invention relates to an electrical insulation construction for a stator for a dynamoelectric machine for ensuring electrical insulation by covering a joint portion surface of conductor wires constituting a stator winding with an electrically-insulating resin.
2. Description of the Related Art
In a conventional stator for an automotive alternator, a stator winding is used in which wave windings are formed by inserting U-shaped conductor segments into pairs of slots from a first axial end of a stator core and welding together end portions of the conductor segments projecting outward at a second axial end of the stator core. In addition, a single electrically-insulating layer is formed by applying a silicone resin so as to cover the welded portions of the conductor segments. Since the modulus of elasticity of the silicone resin is small, it is claimed that the occurrence of insulation failure resulting from exposure of the welded portions to moisture is suppressed and electrical insulation of the stator is improved because cracking and peeling of the electrically-insulating layer resulting from differences in coefficients of expansion between the welded portions and the electrically-insulating layer are reduced. (See Patent Literature 1, for example.)
Patent Literature 1: apanese Patent Laid-Open No. 2000-278901 (Gazette, paragraphs 0005 to 0009.)
In the conventional stator for an automotive alternator, because a single electrically-insulating layer formed so as to cover the welded portions of the stator winding is constituted by a silicone resin having a small modulus of elasticity, one problem has been that the overall rigidity of the coil ends cannot be increased, therefore increasing electromagnetic noise resulting from vibration of the stator brought about by magnetic attraction arising between the stator and the rotor.